Researchers at King’s College London and the University of Reading asked a simple question: what happens when people over 65 get wild blueberries every day for three months?

They published the results in 2023 in the American Journal of Clinical Nutrition.

How the study worked

It involved 61 healthy men and women aged 65 to 80. Half of them drank a daily drink made with 26 g of freeze-dried powder from whole wild blueberries – roughly equivalent to 178 g of fresh blueberries. The other half drank a placebo that looked and tasted the same and had the same fibre, sugar and vitamin C, but no blueberries.

Neither the participants nor the researchers knew who was drinking what. The study ran for twelve weeks.

What the researchers found

Compared with placebo, the people who drank the blueberry drink showed:

• better blood vessel function, meaning the arteries’ ability to widen when the body needs more blood,
• lower systolic blood pressure, by 3.6 mmHg on average, measured over the whole day,
• better immediate word recall, and faster, more accurate responses in attention-switching tasks.

The researchers attribute this to the blue pigments in blueberries, the anthocyanins. They found significantly more of them in the blood and urine of the blueberry group than in the placebo group.

What this does and doesn’t mean

It’s one good-quality study: well designed, blinded and placebo-controlled. It doesn’t mean blueberries cure high blood pressure or stop ageing. There were 61 participants, all healthy and all over 65. In younger people, or in people with health conditions, things may look different.

What’s interesting is that a drink made from whole berries, rather than isolated compounds in capsules, changed measurable things in three months. And that it was wild blueberries – small berries nobody plants, growing on their own on the barrens of Canada and the north-eastern United States.

Wild blueberries also make up 50% of the filling of every gfBar. But the bar is not the drink from the study; it contains a different amount of blueberries, and we don’t attribute the study’s results to it. Why we chose wild blueberries for gfBar is the subject of Wild blueberries from Nova Scotia.

Source: Wood E. et al., Wild blueberry (poly)phenols can improve vascular function and cognitive performance in healthy older individuals: a double-blind randomized controlled trial. American Journal of Clinical Nutrition, 2023. Link to the study